Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
13th MONTHLY
PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - July 2010
1.1
Background
Since 1992, the East of Sha Chau area has been the site of a series of dredged
contaminated mud pits (CMPs) designed to provide
confined marine disposal capacity for contaminated mud arising from the HKSAR’s dredging and reclamation projects. CMP IVc is
presently in operation for backfilling by contaminated mud and is anticipated
to reach its capacity in 2010. A series
of four newly constructed seabed pits at the East of Sha
Chau area, CMP Va-d, will
be provided for the disposal of contaminated mud after CMP IVc
is full. Dredging operations are now
taking place to construct CMP Va-b. The environmental monitoring and audit (EM&A)
programme for the CMPs at the East of Sha Chau area presently covers
disposal operations at CMP IVc and dredging
operations at CMP V.
1.2
Reporting
Period
This Monthly Progress Report
covers the monitoring period of July 2010.
1.3
Details
of Sampling and Laboratory Testing Activities
Demersal Trawling was conducted on 28-29 July
2010 for CMP IVc.
Water Column Profiling was not
conducted for CMP IVc since there was no disposal
activity during the scheduled monitoring events on 27 and 31 July 2010. For CMP V, sampling for Impact Water Quality Monitoring during Dredging Operations was conducted on 2, 5, 7, 9,
12, 14, 16, 19, 23, 26, 28 and 30 July 2010. A summary of field activities are presented in Annex A.
A summary of laboratory
analysis results submitted by the Contractor in this reporting month is
presented in Table 1.1.
Table 1.1 Summary
of laboratory analysis results submitted by the Contractor during the reporting
month
|
Key
Task |
Monitoring
Component |
Results Received from the Contractor |
|
CMP V |
|
|
|
Water Sampling
and Chemical Analysis |
Impact
Monitoring during Dredging Operations |
June’s sampling:
16 July 2010 |
1.4
Details
of Outstanding Sampling and / or Analysis
No outstanding sampling and laboratory analysis remained from July 2010.
1.5
Brief
Discussion of the Monitoring Results
Results of Impact Water Quality Monitoring
during Dredging Operations for July 2010 are presented for CMP V. Detailed results will be discussed in the
relevant Quarterly Reports.
1.5.1
CMP V
Impact Water Quality Monitoring
during Dredging Operations of CMP V – July 2010
Impact
Water Quality Monitoring during Dredging Operations of CMP V was conducted for
three times per week in this reporting month.
On each survey day, sampling was conducted during both mid-ebb and
mid-flood tides at two Reference (Upstream) stations upstream and five Impact (Downstream)
stations downstream of the dredging operations at CMP V. Monitoring was also conducted at the Ma Wan station. At each station, in-situ measurements of water quality parameters as well as water
samples were taken from three depths in the water column (ie
surface: 1 m below sea surface, mid-depth and bottom: 1 m above the seabed).
Monitoring results are presented
in Figures 1 to 48 of Annex B. Generally, levels of DO, depth-average Turbidity
and TSS complied with the Action and Limit Levels set in the Baseline Monitoring Report ([1]) (Table B1 of
Annex B). However,
occasional exceedances of Action and Limit Levels
were recorded. For bottom DO level, isolated
exceedances of Action Level were recorded during the
mid-ebb tide at station DS4 and DS5 on 7 July and at station DS4 only on 9 July
2010. Exceedances
were not recorded for stations DS1-3 which are closer to the dredging works
area, therefore, the exceedances recorded at DS4 and
DS5 are unlikely to be caused by the dredging works of CMP V. For Turbidity, exceedances
of Action Level were recorded at station DS1 during the mid-flood tide on 9 and
12 July 2010. For TSS, exceedances of Limit Level were recorded during the
mid-flood tide at station DS1 on 9 and 12 July while exceedance
of Action Level was recorded at DS3 on 12 July 2010 during the same tidal
period. It should be noted that the
dredging works were undertaken at CMP Va on 9 July
and at CMP Vb on 12 July 2010. On the previous and following sampling days
of these dredging operations (7 and 14 July, respectively), although similar works
were being conducted, there were no exceedances at
any of the above stations. Therefore,
these exceedances were unlikely to be caused by the
dredging works of CMP V.
In accordance with the
requirements of the EM&A Manual, CEDD is in discussion with the
Environmental Protection Department (EPD) as to what appropriate actions are to
be taken due to the record of exceedances of water
quality Action and Limit Levels.
Measures taken will be reported in due course.
1.6
Activities
Scheduled for the Next Month
The following monitoring activities will be conducted in the next monthly period of August
2010:
CMP IVc
·
Water Column Profiling;
·
Routine Water Quality Monitoring;
·
Water Quality Monitoring for Capping Activity;
·
Pit Specific Sediment Chemistry Monitoring;
·
Cumulative Impact Sediment Chemistry Monitoring;
·
Sediment Toxicity Testing;
·
Demersal Trawling; and,
·
Benthic Recolonisation
Monitoring.
CMP V
·
Impact Water Quality Monitoring during Dredging.
The sampling schedule is presented in Annex A.
1.7
Study
Programme
A summary of the Study programme is presented in Annex C.